Stab electrical connector

ABSTRACT

An electrical stab connector includes a plug connector part having a conductive base integrally formed with a plurality of elongated fingers extending longitudinally in angularly spaced, parallel relation. The plug connector part is received in a slotted, circular opening formed in a receptacle connector part. A spring carried by the plug part urges the fingers radially outward into electrically contacting engagement with the opening sidewall. The plug part is secured to a device terminal while the receptacle part may be provided by a slotted opening in a busbar.

United States Patent [191 Olashaw Dec.2,1975

[ STAB ELECTRICAL CONNECTOR [75] Inventor: William Francis Olashaw, Plainville,

Conn.

[73] Assignee: General Electric Company,

Schenectady, NY.

[22] Filed: June 19, 1974 [21] Appl. No.: 480,714

[52] US. Cl. 339/252 P; 339/255 R; 339/256 R;

339/277 R [51] Int. Cl? ..H01R 13/16 [58] Field of Search 339/252, 255, 257, 277, 339/256, 258

[56] References Cited FOREIGN PATENTS OR APPLICATIONS 929,674 6/1963 United Kingdom 339/252 P 1,231,373 4/1960 France 339/252 P Italy 339/252 P Switzerland 339/252 P Primary Examiner-Joseph H. McGlynn Attorney, Agent, or FirmR. A. Cahill; W. C. Bernkopf; F. L. Neuhauser [57] ABSTRACT An electrical stab connector includes a plug connector part having a conductive base integrally formed with a plurality of elongated fingers extending longitudinally in angularly spaced, parallel relation The plug connector part is received in a slotted, circular opening formed in a receptacle connector part. A spring carried by the plug part urges the fingers radially outward into electrically contacting engagement with the opening sidewall. The plug part is secured to a device terminal while the receptacle part may be provided by a slotted opening in a busbar.

5 Claims, 3 Drawing Figures U.S. Patent Dec. 2, 1975 3,923,366

STAB ELECTRNIAL CONNECTOR BACKGROUND OF THE lN /ENTlON Stab or plug-in electrical connectors are well known in a wide variety of configurations. in switchboard applications, stab connectors afford the signal advantage of permitting the electrical connection and disconnection of devices, such as circuit breakers, with relative safety while the switchboard is live. Thus, electrical service to other distribution circuits need not be discontinued while maintenance or installation is being performed with respect to one of the circuits of the switchboard.

Several significant drawbacks limit the use of stab connectors in medium to high current applications. A majority of the stab connection configurations currently available tend to run hotter than an equivalent bolted connection. That is, stab connections tend to introduce somewhat more electrical resistance in the circuit and the resulting heat rise in the switchboard can exceed prescribed upper temperature limits. To com bat this, stab connectors are designed for increased contact pressure, with the result that connection and disconnection can not be readily effected without the mechanical assistance of so-called racking or drawout mechanisms, which can be unjustifiably expensive.

It is accordingly an object of the present invention to provide an improved electrical stab connector.

An additional object is to provide a stab electrical connector of the above character which is designed to run cooler than prior art stab connectors.

Still another object is to provide a stab connector of the above character wherein the functional forces to be overcome incident to connection and disconnection are minimized.

Yet another object of the invention is to provide a stab connector of the above character which is inexpensive to manufacture and efficient and reliable in application.

Other objects of the invention will in part be obvious and in part appear hereinafter.

SUMMARY OF THE lNVENTlON In accordance with the present invention, there is provided a plug-in or stab electrical connector of improved design. in contrast with prior art approaches, the plug connector part of the stab connector is integrally formed of electrically conductive metal, such as copper, aluminum, or related alloys, to provide a plurality of elongated fingers extending longitudinally from a base in angulariy spaced, parallel interrelation. The base is structured for convenient mounting and electrical connection to an electrical device terminal by suitable means, such as a bolted joint. The receptacle part of the stab connector of the invention is simply constituted by a formed circular opening in a conductive plate-like member, which may be a strap mounted in electrically conductive engagement with a busbar or the busbar itself. The diameter of this opening is some what less than the peripheral diameter of the circularly arrayed plug fingers. A spring carried by the plug connector part uniformly urges the fingers radially outward, such that good electric contacting engagement of the fingers with the receptacle opening sidewall is achieved upon insertion of the plug connector part.

. with the consequence that the radially outward spring 0 forces vary drastically at points distributed about the spring circumference.

As an additional feature of the present invention, the receptacle opening is slotted so as to provide the receptacle with a measure of flexibility to further enhance the intimacy of the electrical contacting engagement between the plug and the receptacle.

The invention accordingly comprises the features of construction and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.

DESCRlPTlON OF THE DRAWING MG. 1 is a longitudinal sectional view of a stab electrical connector constructed according to an embodiment of the invention;

H6. 2 is a sectional view taken along line 22 of HG. l; and

FIG. 3 is a perspective view of the spring incorporated in the stab connector of FIG. 1.

DETAILED DESCRIPTION The stab electrical connector of the present invention includes, as seen in FIG. 1, a plug connector part and a receptacle connector part, generally indicated at it} and i2, respectively. Plug connector part 10, formed of a highly conductive metal such as copper, aluminum, or related alloys, includes a base 14 integrally supporting a plurality of annularly arrayed fingers 16 extending longitudinally in parallel, angularly spaced relation. Base 14 is formed with a centrally locatcd aperture ill, preferably square in cross-section, for accepting a square shouldered bolt 20 to mount and electrically connect the plug connector part ll) to a terminal strap 22 of an electrical device 24, such as a circuit breaker.

The annularly arrayed fingers l6 plug into a circular hole 26 formed in receptacle connector part 32. it will be appreciated that the receptacle part may be constituted by a busbar or a strap suitably connected to a busbar, such as with a bolted joint (not shown). The tips of the fingers in are chamfered, as indicated at 28, while hole 26: is countersunk, as indicated at 36) to facilitate insertion. The longitudinal edges along the terminal portions of the fingers are relieved, as indicated at 32 (H6. 2), leaving lands 34 for engagement with the sidewall of hole 326 in receptacle part 112. This insures good electrically contacting engagement between the plug and receptacle connector parts, while reducing the forces required for connection and disconnection.

As an important feature of the invention, receptacle connector part 12 is provided with a slot 36 extending from the part edge into the hole 26. The utilization of a slotted hole affords a measure of flexibility to the receptacle part, likewise formed of copper, aluminum, or related alloys, such that the hole diameter can expand somewhat incident to insertion of the plug part and then contract into positive electrical contacting engagement with fingers 16. This feature further enhances the electrical integrity of the stab connection, while additionally facilitating connection and disconnection.

To impart greater resiliency to fingers 16, a spring 40 is lodged in an annular grove constituted by a series of notches 42 formed in the inner surface of each finger at a location adjacent the tip thereof. Spring 40 is uniquely configured to exert a substantially equal outward radial force on each finger, thus to insure a uniform electrical contacting engagement of each finger with the sidewall of hole 26 in receptacle part 12. To this end, the spring, as best seen in FIGS. 2 and 3, is of a double loop configuration having a first, smaller loop 44 formed at its mid-length, with its end portions formed into a second, larger loop 46 conforming to the inner, diameter of the annular groove in which the spring is lodged. Terminal portions of the spring circumferentially overlap with terminations 48 turned inward so as to permit non-binding movements in notches 42 in fingers 16 during spring flexure. It is found that this spring configuration avoids the tendency of conventional expansion coil springs to flex about a pivot point, resulting in a drastic inequality of the forces acting on the individual fingers 16, It will be appreciated that the resulting non-uniformity in the contact pressure between the individual fingers in the receptacle hole 26 would severely jeopardize the electrical integrity of the connection and its ability to run cool.

It will thus be seen that the objects set forth above, among those made apparent in the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. An electrical stab connector comprising, in combination:

A. a plug connector part having 1. a base,

2. a plurality of individual, elongated fingers integrally formed with said base, said fingers arranged in a circular array and extending longitudinally in angularly spaced, parallel relation, and

4 3. means formed in said base facilitating mounting and electrical connection of said plug connector part to a current carrying part;

B. an essentially plate-like receptacle connector part having first means forming a circular opening therein conforming to the outer diameter of said circularly arrayed fingers and second means form ing a slot in said receptacle part extending from an exterior edge thereof into said opening, whereby said opening expands as said fingers are inserted en masse into said opening; and

C. a double looped coil expansion spring with one loop of larger diameter than the other, said spring disposed internally of said fingers for urging said fingers individually radially outward into electrically contacting engagement with the sidewall of said opening to complete a stab electrical connection.

2. The connector defined in claim 1, wherein a portion of the peripheral surface of each said finger is relieved to enhance the quality of electrically contacting engagement of said fingers with said sidewall of said opening.

3. The connector defined in claim 1, wherein said plug connector part includes means forming a notch in the internal surface of each said finger, said notches being circumferentially aligned to provide an annular groove accommodating said spring.

4. The connector defined in claim 3, wherein said receptacle opening is countersunk, and the tips of said fingers are chamfered to facilitate insertion of said fingers in said opening.

5. In a stab electrical connector, a plug connector part for stab electrical connection with the receptacle connector part, said plug connector part comprising, in combination:

A. a base;

B. a plurality of individual, elongated fingers integrally formed with said base, said fingers arranged in a circular array and extending longitudinally in angularly spaced, parallel relation;

C. means formed in said base facilitating mounting and electrical connection of said plug connector part to a current carrying part; and

D. a spring disposed internally of said fingers and operative to individually bias said fingers radially outward, said spring being in the form of a double looped coil expansion spring with one loop of larger diameter than the other. 

1. An electrical stab connector comprising, in combination: A. a plug connector part having
 1. a base,
 2. a plurality of individual, elongated fingers integrally formed with said base, said fingers arranged in a circular array and extending longitudinally in angularly spaced, parallel relation, and
 3. means formed in said base facilitating mounting and electrical connection of said plug connector part to a current carrying part; B. an essentially plate-like receptacle connector part having first means forming a circular opening therein conforming to the outer diameter of said circularly arrayed fingers and second means forming a slot in said receptacle part extending from an exterior edge thereof into said opening, whereby said opening expands as said fingers are inserted en masse into said opening; and C. a double looped coil expansion spring with one loop of larger diameter than the other, said spring disposed internally of said fingers for urging said fingers individually radially outward into electrically contacting engagement with the sidewall of said opening to complete a stab electrical connection.
 2. a plurality of individual, elongated fingers integrally formed with said base, said fingers arranged in a circular array and extending longitudinally in angularly spaced, parallel relation, and
 2. The connector defined in claim 1, wherein a portion of the peripheral surface of each said finger is relieved to enhance the quality of electrically contacting engagement of said fingers with said sidewall of said opening.
 3. The connector defined in claim 1, wherein said plug connector part includes means forming a notch in the internal surface of each said finger, said notches being circumferentially aligned to provide an annular groove accommodating said spring.
 3. means formed in said base facilitating mounting and electrical connection of said plug connector part to a current carrying part; B. an essentially plate-like receptacle connector part having first means forming a circular opening therein conforming to the outer diameter of said circularly arrayed fingers and second means forming a slot in said receptacle part extending from an exterior edge thereof into said opening, whereby said opening expands as said fingers are inserted en masse into said opening; and C. a double looped coil expansion spring with one loop of larger diameter than the other, said spring disposed internally of said fingers for urging said fingers individually radially outward into electrically contacting engagement with the sidewall of said opening to complete a stab electrical connection.
 4. The connector defined in claim 3, wherein said receptacle opening is countersunk, and the tips of said fingers are chamfered to facilitate insertion of said fingers in said opening.
 5. In a stab electrical connector, a plug connector part for stab electrical connection with the receptacle connector part, said plug connector part comprising, in combination: A. a base; B. a plurality of individual, elongated fingers integrally formed with said base, said fingers arranged in a circular array and extending longitudinally in angularly spaced, parallel relation; C. means formed in said base facilitating mounting and electrical connection of said plug connector part to a current carrying part; and D. a spring disposed internally of said finGers and operative to individually bias said fingers radially outward, said spring being in the form of a double looped coil expansion spring with one loop of larger diameter than the other. 